H2 Receptor Antagonists Flashcards

1
Q

Give 2 examples of H2 receptor antagonists?

A
  • Ranitidine

- Cimetidine

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2
Q

What is the action of H2 receptor antagonists?

A

Reduce gastric acid production by binding to H2 receptors and blocking them

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3
Q

How are H2 receptor antagonists administered?

A

Oral

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4
Q

What are the indications for H2 receptor antagonists?

A
  • Peptic ulcers
  • Duodenal ulcers
  • GORD
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5
Q

What are the cautions for the use of H2 receptor antagonists?

A

Renal impairment

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6
Q

When should the dose of a H2 receptor antagonist be halved?

A

eGFR <50 ml/min

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7
Q

What drugs can cimetidine interact with?

A
  • Warfarin
  • Phenytoin
  • Theophylline
  • Carbamazepine
  • Sodium valproate
  • Clopidogrel
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8
Q

How does cimetidine interact with clopidogrel?

A

Reduces its antiplatelet effects

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9
Q

How does cimetidine interact with warfarin, phenytoin, theophylline, carbamazepine and sodium valproate?

A

By inhibiting the CYP450 enzymes and reducing their metabolism

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10
Q

What is the effect on the drugs metabolised by CYP450 enzymes of cimetidine?

A

Increases their effects

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11
Q

When should investigations be undertaken before starting H2 receptor antagonists?

A

When suspicious symptoms for gastric cancer

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12
Q

What are the commons side-effects of H2 receptor antagonists?

A
  • Headache
  • Dizziness
  • Diarrhoea
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13
Q

What are the less common side-effects of H2 receptor antagonists?

A
  • Rashes
  • Confusion
  • Depression
  • Bleeding disorders
  • Gynaecomastia
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14
Q

What mnemonic can be used to remember drugs that can cause gynaecomastia?

A

DISCO

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15
Q

What does DISCO stand for?

A
  • Digoxin
  • Isoniazid
  • Spironolactone
  • Cimetidine
  • Oestrogens
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16
Q

What patients counselling should be given when prescribing H2 receptor antagonists?

A
  • How to further reduce acidity

- Red flag symptoms of gastric cancer

17
Q

How can acidity be further reduced?

A
  • Avoid foods and drinks that worsen symptoms

- Avoid lying flat after eating